Device for projecting pulverulent materials by means of a plasma torch



Oct. 18, 1966 G. MONDAlN-MO AL ETAL 3,280,295

DEVICE FOR R JEC G PU RULENT MATERIALS BY ANS A PLASMA TORCH Filed July 1, 1963 2 Sheets-Sheet 1 Oct. 18, 1966 G. MONDAlN-MONVAL ETAL 3,280,295

DEVICE FOR PROJECTING PULVERULENT MATERIALS BY MEANS OF A PLASMA TORCH Filed July 1, 1963 2 Sheets-Sheet 2 United States Patent Claims. 2:1. 21976) The present invent-ion relates to a device for the projection of pulverulent metallic or refractory materials by means of a jet of ionized gases and brought to very high temperature by a constricted electric arc (plasma), the pulverulent material being introduced into the gas jet of the arc by an auxiliary gaseous current in which the powder to be projected is in suspension. Apparatus of this type is already known in which the gaseous current containing the powder in suspension is injected into the main jet through a radial conduit opening into the end portion of the projection nozzle. However, this arrangement only enables a homogeneous distribution of the powder in the gas jet to be obtained by means of delicate and diiiicult adjustments.

The apparatus forming the subject of the present invention enables this disadvantage to be overcome and it is characterised in that the supply conduit for the pulverulent material in suspension in this auxiliary gaseous current opens into the apparatus upstream of the neck of the nozzle through which escapes the gas jet of the arc and is disposed on the one hand at an angle less than or equal to 45 in relation to the axis of said nozzle, while on the other hand the axis of this conduit does not meet the electrode from whence the arc strikes.

Due to the powder being injected upstream of the nozzle neck, this powder is in contact for a longer time and in more intimate manner with the gas column of the arc, this powder is distributed more regularly in this column, and in addition the fusion of the powder is effected because of this prolonged contact with a better yield and can be obtained with a lower electrical power.

By way of example, several embodiments of the apparatus according to the invention are hereinafter described and illustrated in the accompanying drawing.

FIGURE 1 is an axial section of a first embodiment of the invention as applied to a plasma apparatus.

FIGURE 2 is a perspective view, partly broken away, showing a second embodiment with a transverse nozzle.

FIGURE 3 is an axial section of a third embodiment comprising an adjustable nozzle.

In the example shown in FIGURE 1, which represents a plasma torch adapted to project a material in the form of powder, the conduit for introducing the powder into the plasma jet is so dis-posed that an extension thereof does not meet either the walls of the nozzle or the cathode, in order to avoid depositions on these elements of the fused pulverulent material. In this example, the apparatus com-prises a body 1 having a cooling water circulation 2, 3 and axially of which is formed a bore 4 containing the cathode 5 and into which is blown the gas which will be ionized and brought to high temperature by the arc striking from the cathode 5. The bore 4 opens on to an outlet face 6, which is oblique relatively to the axis of the cathode 5 and the said bore and on to which also opens the supply conduit 7 for the powdered material, which conduit is disposed obliquely in relation to the axis of the cathode 5, and at a relatively small acute angle, so that the extension of this conduit does not meet the point of the cathode penetrating into the cone 8 of the discharge nozzle for the jet, the body 9 of said jet being provided with a cooling circuit '10,

3,230,295 Patented Oct. 18, 1966 11 and being fixed by suitable known means against the outlet face 6. The position of the cathode 5 is regulated so that its point is located on the axis of the cone 8, which has its lower vgeneratrix disposed in the extension of the lower tgeneratrix of the bore 4, while its axis is disposed practically parallel to the bisector of the angle formed by the bore 4 and the conduit 7, and slightly below this bisector, so that the pulverulent material projected through the conduit 7 does not come into contact with the wall of the cylindrical part 12 of the nozzle adjoining the cone 8. The nozzle of the jet is the cavity having an entrance cone 8 and a cylindrical portion v12.

In the embodiment shown in FIGURE 2, the apparatus comprises a lateral projection nozzle, i.e., a nozzle perpendicular to the longitudinal axis of the apparatus, and this arrangement is particularly useful in the case where the projected pulverulen-t material is to "form a lining of the internal wall of a bore or of a hollow body. In this embodiment, the cylindrical body '13 of .the apparatus comprises an internal axial tube 14 serving as the mounting for the cathode 15 and for the passage of the gas which is intended to form the plasma jet. Connected to the body 13 by means of a fluidtight joint 16 is a delivery member comprising a likewise cylindrical body 17 in which is formed a radial projection nozzle 18, of which the inlet funnel 19 opens into an axial bore 20 forming a seating for the tube '14 containing the cathode '15, the tip 21 of which is located on the axis of the nozzle 18. A supply conduit 22 for the pul verulen't material to be projected opens into the entry cone 19 of the nozzle at the top and from the side opposite to the exit of the nozzle.

Mounted on the body 17 by means of a packing 23 is a hollow cap 24, the interior of which communicates with longitudinal ducts 25, 25' formed in body 17 and forming part of the cooling circuit.

The body 17 and the cap 24 are connected to the body 13 of the apparatus by means of studs 26 and nuts 27.

In the embodiment shown in FIGURE 3, the apparatus is equipped with an adjustable nozzle which enables the plasma jet entraining the material in powder form to be directed in all directions between that of the longitudinal axis of the apparatus and a direction perpendicular to the latter, so as to permit the apparatus to be used for the treatment of external and internal surfaces of elements of very diiferent shapes.

This type ef torch with an adjustable nozzle forms the subject of the French patent application in the name of the applicants, No. RV. 903,014, dated July 5th, 1962.

As shown in the drawings, the body 28 of the apparatus carrying the electrode 29 has mounted thereon a delivery portion which is formed by a tubular part 30 having an axis X'-X and connected to the apparatus 28 through the joint 31 by means of a locking nut 32. Fixed on the end of the tube 30 is a plate 33 which is inclined at 45 relatively to the axis of the tube 30 and of the electrode 29, this plate having an oblique opening 34 extending the bore of the tube 30; formed on its periphery is a groove 35 receiving a packing ring '36, by means of which an adjustable head 37 is mounted on the plate 33, the said head being able to turn about the axis Y'-Y of the plate 33. Formed in the head 37 is a projection nozzle 38, having an axis Z'Z which forms an angle of 45 with the axis of rotation YY and the inlet 39 of which is connected to the opening 34 and to the tube 30; a supply conduit for the powder also opens into this inlet 39, said conduit being disposed perpendicularly on the axis of rotation Y'Y.

It is seen that if the axis Z'Z of the projection nozzle is perpendicular to the axis X'X of the apparatus, as in the position shown in the drawing, a rotation of .the head 3 37 through 180 will bring the axis ZZ of the nozzle into the position symmetrical with the position shown in relation to the axis Y-Y, i.e., into the extension of the tube 30.

What we claim is:

1. Apparatus for the project-ion of pulver-ulent materials by means of a jet of ionized gas brought to a very high temperature by a constricted electric arc, comprising a nozzle, a supply conduit for the pulvenulent material opening into the nozzle upstream of the neck of the nozzle and making an angle of not more than 45 with the axis of the nozzle, and an electrode extending into the nozzle with the tip of the electrode spaced from the axis of the supply conduit, the axes of the supply conduit and electrode making an acute angle with each other and with the axis of the nozzle, the angle of the supply conduit axis with the nozzle axis being smaller than the angle of the electrode axis with the nozzle axis.

2. An apparatus as claimed in claim 1 wherein an extension of the axis of the supply conduit extends through the nozzle exit.

3. Apparatus for the projection of pulverulent materials by means of a jet of ionized gas brought to a very high temperature by a constricted electric arc, compnising a nozzle, a supply conduit for the pulverulent material opening into the nozzle upstream of the neck of the nozzle and making an angle of not more than 45 with the axis of the nozzle, and an electrode extending into the nozzle with the tip of the electrode spaced from the axis of the supply conduit, said nozzle comprising a conical inlet chamber, means mounting the electrode in a tube, the entry cone of said nozzle being connected to said tube by one of its generatrices disposed in the extension of the lower generatrix of the tube.

4. Apparatus for the projection of pulverulent materials by means of a jet of ionized gas brought to a very high temperature by a constricted, electric arc, comprising a nozzle, a supply conduit for the pulverulent material opening into the nozzle and substantially aligned with .the axis thereof, and an electrode extending into the nozzle laterally thereof with the tip of the electrode spaced from the tubular projection of the conduit.

5. Apparatus for the projection of pulverulent materials by means of a jet of ionized gas brought to a very high temperature by a constricted electric arc, comprising a nozzle, a supply conduit for the pulverulent material opening into the nozzle upstream of the neck of the nozzle making an angle of not more than 45 with the axis of the nozzle, and an electrode'extending into the nozzlewith the tip of the electrode spaced from the axis of the supply conduit, means mounting the nozzle and supply conduit for rotation about an axis inclined relative to the axis of the electrode, the axis of the supply conduit being perpendicular to said axis of rotation.

References Cited by the Examiner UNITED STATES PATENTS 2,973,426 2/1961 Casey 2l9--75 3,071,678 1/1963 Neeley et a1 219--76 3,179,782 4/1965 Matvay 21976 3,183,337 5/1965 Winzeler et a]. 21976 3,197,605 7/1965 Sunnen 219-76 ANTHONY BARTIS, Acling Primary Examiner.

JOSEPH V. TRUHE, RICHARD M. WOOD,

Examiners. 

4. APPARATUS FOR THE PROJECTION OF PULVERULENT MATERIALS BY MEANS OF A JET OF IONIZED GAS BROUGHT TO A VERY HIGH TEMPERATURE BY A CONSTRICTED ELECTRIC ARC, COMPRISING A NOZZLE, A SUPPLY CONDUIT FOR THE PULVERULENT MATERIAL OPENING INTO THE NOZZLE AND SUBSTANTIALLY ALIGNED WITH THE AXIS THEREOF, AND AN ELECTRODE EXTENDING INTO THE NOZZLE LATERALLY THEREOF WITH THE TIP OF THE ELECTRODE SPACED FROM THE TUBULAR PROJECTION OF THE CONDUIT. 